Altec Lansing 6 x 9-4C
Best box: 34.0 L bass reflex tuned to 48.4 Hz · F3 64.7 Hz
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Comparable 6.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the Altec Lansing 6 x 9-4C does not fit your target box volume or tuning. Each entry links to its full enclosure design and Thiele/Small parameters.
⚠️ Engineering Notice for Builders
- Limited linear excursion (Xmax: 2.032 mm); set a high-pass subsonic filter at 25–30 Hz when driven with high power.
Recommended Bass Reflex (Vented)
PORT BUILDABLE| Net Box Volume (Vb) | 34.0 Liters |
| Tuning Frequency (Fb) | 48.4 Hz |
| F3 (-3 dB Cutoff) | 64.7 Hz |
| F6 / F10 Extension | 53.0 Hz / 41.1 Hz |
| Port Inner Diameter | Ø 5.0 cm |
| Port Physical Length | 3.8 cm |
| First Pipe Resonance | 4509.0 Hz |
| Estimated MOL @ F3 | 102.3 dB SPL |
Sealed (Acoustic Suspension) — compromise
SUITS INFINITE / OPEN BAFFLEWith Qts 0.63 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 0.891; for a flat response this driver is better used on an infinite (IB) or open baffle.
| Net Box Volume (Vb) | 42.5 Liters |
| System Q (Qtc) | 0.891 (above Butterworth) |
| System Resonance (Fc) | 80.5 Hz |
| F3 (-3 dB Cutoff) | 66.7 Hz |
| F6 / F10 Extension | 53.7 Hz / 42.3 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 56.9 Hz |
| Total Q (Qts) | 0.63 |
| Electrical Q (Qes) | 0.803 |
| Mechanical Q (Qms) | 2.92 |
| Equivalent Volume (Vas) | 42.5 Liters |
| Diaphragm Area (Sd) | 185.5 cm² |
| DC Resistance (Re) | 2.8 Ω |
| Efficiency Bandwidth Product (EBP) | 70.8 |
| Linear Excursion (Xmax) | 2.0 mm |
| Thermal Power (Pe) | N/A W |
| Nominal Diameter | 6.0" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for Altec Lansing 6 x 9-4C?
Load Forge's calculated alignment puts Altec Lansing 6 x 9-4C in a 34.0 liter vented enclosure tuned to 48.4 Hz, reaching an F3 cutoff of approximately 64.7 Hz.
Can Altec Lansing 6 x 9-4C be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 42.5 liters with a Qtc of 0.891 (above Butterworth), the system exhibits an F3 of 66.7 Hz.
What port dimensions should be used for Altec Lansing 6 x 9-4C to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 5.0 cm with a length of 3.8 cm is suggested; check the port air velocity at your drive level in the Load Forge Studio.
Shareable Acoustic Card for Forums & Social Media
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